Atrazine is a major herbicide of the s-triazine family which has been extensively used in North America over the last 30 years. According to the U.S. EPA, atrazine is a possible human carcinogen. USDA found atrazine mutagenic in 50% of microbial assays reviewed. Photolysis and microbial degradation may be important degradative processes affecting atrazine in aquatic environments. However, formation of mutagens by photolysis of aromatic pollutants is likely to occur in aquatic environments containing agricultural nutrients such as nitrate. The hypothesis to be tested is that a combination of sun- lit photolysis and microbial degradation can be developed to detoxify atrazine in surface aquatic systems. The general approach of this project is to use microbial bioassays in conjunction with chemical identification and analysis procedures to determine the fates and effects of atrazine and its photo products in surface aquatic systems. Testing of the ecotoxicity will be conducted with assays of microbial activities and biomass. Conditions favoring complete and fast removal of atrazine will be exploited, hence economical remediation technologies will be developed to minimize the impact of the test pollutant on human health. The specific aims are: (1) To determine the ecotoxicity of atrazine and its photo products in natural aquatic environments with microbial bioassays; (2) To determine the effect of seasons/temperature, pH, selected sensitizers, concentration of nitrate/nitrite, concentrations of ferric/ferrous salts, and humic substances of the persistence and toxicological properties of the test compounds; (3) To develop economical remediation technologies to reduce the environmental loading of atrazine and its photo products. The long-term objectives are: (1) To produce the data base of the ecosystem health assessment of atrazine and to provide more accurate methods to minimize the impact of the test compounds on human health; (2) to enhance the level of research excellence and standards of academic performance of Jackson State University in the areas of biomedical and environmental sciences; (3) to further strengthen collaborative research efforts between JSU and US Army Corps of Engineers Waterways Experiment Station at Vicksburg, Mississippi.